An eyewitness’s identification of an accused defendant often provides some of the most dramatic and powerful evidence in a criminal case. “Do you see in this courtroom the person you saw fire the fatal shot?” asks the prosecutor. “Yes,” says the eyewitness, pointing to the defendant, adding for good measure, “I will never forget his face.”
But in fact the eyewitness is frequently wrong: inaccurate eyewitness identifications appear to be the single greatest contributor to wrongful convictions. For example, they were introduced as evidence in over 70 percent of the more than 360 cases that the Innocence Project, using DNA analysis, later proved were wrongful convictions. Nearly a third of these cases, moreover, involved multiple misidentifications of the defendant. By comparison, the next-most-frequent contributor to wrongful convictions, misleading testimony by forensic “experts,” was present in 45 percent of these cases, and the third-most-frequent factor, false confession, was present in about 30 percent of them.
While some eyewitnesses have had prior contact with the person they identify as the perpetrator of a crime (as when a neighbor sees a husband abusing his wife), many have had none and only see the defendant once, when they witness the crime. But in some respects this makes their testimony stronger, for they have no motive to lie. The defendant was a complete stranger to them, and they simply had the misfortune to have been a passer-by or, worse, a victim. In either case, the encounter was not something they were likely to forget—and the jury generally finds their testimony believable.
Why are eyewitnesses so often wrong? Improper police practices sometimes play a part, as when a police officer conducting a line-up urges the eyewitness to “take a good look at number 3,” or when the eyewitness only tentatively identifies the person in the line-up that the officer suspects is the culprit and the officer says, “Good work.” But the chief causes of inaccurate eyewitness identifications are shortcomings inherent in human perception and memory that cannot be eliminated easily, if at all. Some of these are obvious. The ability of an eyewitness to perceive the face of a culprit will be affected by lighting, by distance and angle, by the acuity of the eyewitness’s eyesight, by the amount of time the eyewitness looked at the culprit, and by distractions such as a gun. Similarly, memories tend to fade over time, which may affect how accurately an eyewitness can remember a face seen many hours, days, or even weeks earlier.
Considerable research indicates, however, that many people overrate their ability to perceive and remember faces they saw only once, and that what they remember mostly relates to some general characteristic, such as that the culprit was square-jawed or had a mustache.1 The research also shows that there are many other factors that can influence and distort an eyewitness’s perceptions and recollections. For instance, careful…
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